Q: Tuning Air/Fuel Mixture on 1977 Bus with Fuel Injection

[equinox]

Thank you. I will do as you suggested and take for a ride and report the graph and results via the datalogger again. Stay tuned.

p.s. - Is it best to loosen the spark plugs on this engine when hot and everything expanded or the other way around and cool?

[SGKent]

some like it hot, some like it cold. I like it cold to medium warm. As you loosen them you do not go any further then they want to turn gently once they start turning. If you feel any resistance building you gently move them tighter again until they are free again, and then try to loosen them again. You do that tight - loose sequence as many times as needed to get them out. If you force them you will damage the threads. If you have a Cyl Temp gauge it will probably have a ring under one of the plugs - usually #3. If you run into trouble you stop, retighten the plug and do it another day. It can require penetrating oil if the plug threads are carboned up.

T4 plugs are at a weird angle

_________________
“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[equinox]

Ok, no dice yet. Too many other chores and time ran out and I'm heading up North and taking the bus on vacation. It's going to eat gas, but it is what it is. I didn't want to get in it and then have any issues and not able to take it, so I'll get into it when I get back after the weekend.

p.s. - I just ordered the inductive pickup from Summit Racing to monitor the RPM on the LM-2. Not sure why I didn't see it before, but it's ordered as of Thursday morning.

[equinox]

Ok, back from weekend up north!

The inductive pickup came in from Summit Racing and I just checked it out really fast, so now I will be able to monitor Air Flow AND at RPM as requested!

I have a little larger concern right now thou as while I was up North, when I put the thing in Reverse, it didn't do anything and I had to half throttle it to get it to go and when off the gas would come to a stop like brakes were being applied! Later, I was riding in Drive and at 40-45MPH the RPMs were higher than normal!...it did pop in, but later I wanted to see how first was going and I put it in and gave it gas and nothing! I put in Drive and ok and made it home no problem. Reverse was intermittent working some times and not others. Any ideas what would cause this? It's almost like the indexing is off. I hope nothing wrong with the clutches inside. How about too much fluid?

Let me know about this one. This will need to be fixed and I hope I don't have to take it to the hacks tomorrow!

[Randy in Maine]

I will defer to someone who knows about the auto trans. Does the trans fluid look or smell burnt?

[equinox]

No, fluid color and smell look good!

[equinox]

...just circling back to this from last year. I still need to set the AFM, but currently fixing the auto trans having it and the final gear rebuild, new rear seal and torque converter, etc!

Once I get it back from the trans guy, I'll work on solving the AFM issue and hopefully head out for the first camping expedition!

I'll keep you posted.

[equinox]

Ok, after a year of hiadis, I'm back!

Since that time, I lost reverse and had the transmission and final gear assemblies completely rebuilt (as well as torque converter replaced), which cost me $2600!

After it was complete and any "slippage" that may have occured from the drivetrain, I calculated the milage as around 12.5MPG (from 19.5MPG when I first got the bus)!

Since the AFM had sime work done to it as I had indicated (flap blew out due to backfire) and some adjustment from the previous mechanic and being 40 years old, I decided to get the AFM completely rebuilt by Fuel Injection Coporation in California! I sent it out and got it back and installed on Monday of this week!

The AFM unit looks FANTASTIC. I expected to install it at it to be at least the same if not better. However, it's WORSE!! Itwon't even hold idle!!

I need you help in diagnosing and fixing this. I can note visually that the settings do not appear to be different, so I'm wondering if 1. the AFM was rebuilt wrong or 2. now that it IS working 100%, if the settings they had to put it at to get it working before are now way out of wack and causing the current condition??!?

Attached are photos of the before and after photos of the AFM along with a video so you can see and hear what it's doing. PLEASE ADVISE and I pray, it only needs adjustment and finally get this things working and able to use it after 3 years!!! :O As it only runs for a few seconds, I have no idea if it's rich or lean or what?!?

http://s934.photobucket.com/user/rroza/slideshow/VW%20Bus/AFM

http://vid934.photobucket.com/albums/ad185/rroza/VW%20Bus/AFM/IMG_2490.mp4

BUMP

[Tcash]

Seems like the fuel pump is not kicking on.

When you first start it, the fuel pump is powered by the starter. Once it is started afm flap opens and powers the fuel pump.

Key on pull the air filter out. Take a chop stick and open the flap on the AFM.
You should hear the fuel pump kick on.
No fuel pump, flap still open, wiggle the connector on the AFM, wiggle the connectors on the double relay.

Good luck
Tcash

Double Relay Explained. . . In Color!
http://www.thesamba.com/vw/forum/viewtopic.php?t=334340&highlight=

[SGKent]

did you remember to plug it in during the excitement?
_________________
“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[equinox]

Ok, I unsnapped the 4 levels and disconnected the aircleaner housing from the unit and used a long wood BBQ skewer (same difference as chopstick) to open the door. Not sure what "flap" you're talking about.

I fired it up, again ran for like 3 seconds and died. I turned it off and then to on again (this time not firing it up) and advanced the door. I heard somethinf on the left (drivers side) and assuming fuel pump, but did it a few time and could not hear anything every time. Only like that one time.

I tried taking the connector off and on, no difference. I also removed the black top and silicon from the AFM, so I could advance the mechanism by hand.

I don't know if this means anything, but there is a connection while the unit is in the closed position and opens when away from that position. I'm assuming this is triggering the fuel pump??!? (see photo - photobucket rotated it 180 degrees for whatever reason, but whatever)

The bus ran BEFORE the rebuild, so only thing swapped out was the AFM. It's a bus and old and sure something else could fail, but I'm assuming it has to do with the rebuild or in that the settings, but let's find out. I need it running and it's not even diong that right now!! :O

http://i934.photobucket.com/albums/ad185/rroza/VW%20Bus/AFM/IMG_2515b.jpg

[Tcash]

Sorry to say. You probably voided any kind of warranty removing the AFM cover.
The cover requires a specific sealant so it does not contaminate the carbon track.

You will only hear the pump run for a short bit and then it will stop once the pump has built pressure.
If you don't know where your fuel pump is. You need to get under the left side side of the vehicle and find it. Put your hand on it while someone opens the flap for you.
You need to run the pressure out of the fuel system.
Run it until it dies, test the pump. You are only going to hear it for a short time. Repeat.

The set of contacts are to turn the fuel pump off and on.
Contacts open fuel pump off
Contacts closed fuel pump on.

You did not unplug the cold start valve or thermo time switch by chance or do any other kind of wiring?

Retest
Tcash

Please do not do any adjustments on the AFM!

[equinox]

"You probably voided any kind of warranty removing the AFM cover. "

Well, it's just silicon, so worst case, I can re-silicon it, but although completely clean, I can see from the set screws and positions of things, there was no alteration to the original settings as sent in, which from last year's forum posts, folks thought is was very far over and needed to be brought to nominal.

Ok, so let me grab a friend as is gonna be needed and report back on the fuel pump. If you guys can post photos, please do so. One issue is terms are used like "flap", "double relay", etc. This is great for a mechanic or VW enthusiest, but for a person not a mechanic by trade and first ever VW owner, this is just about meaningless....without photos. I'm learning a lot, like fuel pump is engaged by contacts in AFM, etc. But because this is my first and again, not mechanic by trade, the curve is long.

Thanks for your help and let me check when I get home. I hope to get working this weekend. We'll see. Once this is resolved, I still need to check the air/fuel ratio and possibly adjust the unit (which means top needs removal anyway). My concern is that NOTHING changed except removal and replacement of the unit and rebuild of it. I'll verify all hoses and what not are attached and post video(s) so you can "see" what's going on also. Thanks for your help.

[Tcash]

Well, it's just silicon
The cover requires a specific sealant so it does not contaminate the carbon track.

Get one of these.
https://www.amazon.com/Volkswagen-Station-Wagon-Se...al+bentley

Air flow sensor flap

VW Dictionary
http://www.thesamba.com/vw/archives/dic/

FI Components

[SGKent]

the acetic acid inside RTV silicone off gases acidic compounds that slowly damage the AFM. Tape the top on or buy the non-acidic / non-corrosive RTV designed for application around electronics.

example: https://www.amazon.com/GC-Electronic-Silicone-Seal...entries*=0

example:

with the green distributor wire removed to keep from burning your points, turn the key on and open the flap inside the AFM. You should hear the double relay click and the fuel pump come on as long as the flap is opened. There are two contacts inside the AFM that make connection when the flap is opened. I had so many problems with rebuilt AFM's that I bought a new one and spare new one. They sell around $600 to $700 now. You used to be able to find them for around $200 if you watched Ebay and people closing foreign car shops or parts warehouses. You'll have to watch both under the Bosch and VW part numbers. One could come up tomorrow or not until 10 years from now. That is life with a 40 year old car. Most likely you have a vacuum leak - cracked S-boot or something. Build a smoke generator and look for that first.

Here is a photo from Richard Atwell. The contacts are on the far right. The arm opens them when the flap is closed and lets them touch when the flap is opened.

_________________
“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[Tcash]

I don't know if this means anything, but there is a connection while the unit is in the closed position and opens when away from that position. I'm assuming this is triggering the fuel pump??!?

This is opposite of the way it should work.
There should be no connection while the Flap is in the closed position.

The points should close and make connection when the Flap is opened.

Tcash

[equinox]

This is VERY helpful, thanks!

I have the Bentley and Service Manuals, so as far as main books, I'm good!

Ok, great AFM diagram and that backfire flap must be what they repaired a year or two ago. That center thing must be a rubber or something and got blown out during backfire, but currently it looks almost like a slug siliconed on with a screw in the center. Not sure what it looks like "stock", but this helps and identify the components. They temporarily "repaired" this and did some adjustments to the AFM (which appear way over to one side and may need adjusting once get working). It ran previously, so either something off with the rebuild on the AFM or maybe I missed reinstalling something or possibly, but not probable, somehthing just so happened to fail or start to fail like fuel pump??!? The black cover on the AFM indicates it's a 0 280 200 018

I'll look for the ECU and part number. Not sure where this is going as the vehicle worked before the rebuild, but I'll check.

Similarly, but sure what the distributor has to do, but I'll pull the number. This was replaced within the year with an electronic no points one. It's got a Pertronix Ignitor 1847V in it.

I'll check the part numbers when I get home from work. Thanks about the heads up on RTV to use. Right now it's just set in place to keep dust off. When I'm ready to finalize it, I WILL use the appropriate RTV.

[SGKent]

leave adjustments alone until you are sure the system if working correctly otherwise.
_________________
“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[Hoody]

I have a NOS AFM for your Bus. PM me if your interested.

[equinox]

Well, I got tied up last weekend and did not get around to checking the fuel pump unit. I did get a lot of chores done and it was a beautiful weekend, so that is good. I'm in Mexico on business now through the week, so I'll look into it Saturday and report back this weekend. Thanks for everyone's support!